xref: /freebsd/sys/arm/broadcom/bcm2835/bcm2835_sdhci.c (revision 48c779cdecb5f803e5fe5d761987e976ca9609db)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3  *
4  * Copyright (c) 2012 Oleksandr Tymoshenko <gonzo@freebsd.org>
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  *
16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26  * SUCH DAMAGE.
27  *
28  */
29 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD$");
31 
32 #include <sys/param.h>
33 #include <sys/systm.h>
34 #include <sys/bus.h>
35 #include <sys/kernel.h>
36 #include <sys/lock.h>
37 #include <sys/malloc.h>
38 #include <sys/module.h>
39 #include <sys/mutex.h>
40 #include <sys/rman.h>
41 #include <sys/sysctl.h>
42 #include <sys/taskqueue.h>
43 
44 #include <machine/bus.h>
45 
46 #include <dev/ofw/ofw_bus.h>
47 #include <dev/ofw/ofw_bus_subr.h>
48 
49 #include <dev/mmc/bridge.h>
50 #include <dev/mmc/mmcreg.h>
51 
52 #include <dev/sdhci/sdhci.h>
53 
54 #include "mmcbr_if.h"
55 #include "sdhci_if.h"
56 
57 #include "opt_mmccam.h"
58 
59 #include "bcm2835_dma.h"
60 #include <arm/broadcom/bcm2835/bcm2835_mbox_prop.h>
61 #ifdef NOTYET
62 #include <arm/broadcom/bcm2835/bcm2835_clkman.h>
63 #endif
64 
65 #define	BCM2835_DEFAULT_SDHCI_FREQ	50
66 #define	BCM2838_DEFAULT_SDHCI_FREQ	100
67 
68 #define	BCM_SDHCI_BUFFER_SIZE		512
69 #define	NUM_DMA_SEGS			2
70 
71 #ifdef DEBUG
72 static int bcm2835_sdhci_debug = 0;
73 
74 TUNABLE_INT("hw.bcm2835.sdhci.debug", &bcm2835_sdhci_debug);
75 SYSCTL_INT(_hw_sdhci, OID_AUTO, bcm2835_sdhci_debug, CTLFLAG_RWTUN,
76     &bcm2835_sdhci_debug, 0, "bcm2835 SDHCI debug level");
77 
78 #define	dprintf(fmt, args...)					\
79 	do {							\
80 		if (bcm2835_sdhci_debug)			\
81 			printf("%s: " fmt, __func__, ##args);	\
82 	}  while (0)
83 #else
84 #define dprintf(fmt, args...)
85 #endif
86 
87 static int bcm2835_sdhci_hs = 1;
88 static int bcm2835_sdhci_pio_mode = 0;
89 
90 struct bcm_mmc_conf {
91 	int	clock_id;
92 	int	clock_src;
93 	int	default_freq;
94 	int	quirks;
95 	bool	use_dma;
96 };
97 
98 struct bcm_mmc_conf bcm2835_sdhci_conf = {
99 	.clock_id	= BCM2835_MBOX_CLOCK_ID_EMMC,
100 	.clock_src	= -1,
101 	.default_freq	= BCM2835_DEFAULT_SDHCI_FREQ,
102 	.quirks		= SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK |
103 	    SDHCI_QUIRK_BROKEN_TIMEOUT_VAL | SDHCI_QUIRK_DONT_SET_HISPD_BIT |
104 	    SDHCI_QUIRK_MISSING_CAPS,
105 	.use_dma	= true
106 };
107 
108 struct bcm_mmc_conf bcm2838_emmc2_conf = {
109 	.clock_id	= BCM2838_MBOX_CLOCK_ID_EMMC2,
110 	.clock_src	= -1,
111 	.default_freq	= BCM2838_DEFAULT_SDHCI_FREQ,
112 	.quirks		= 0,
113 	/* XXX DMA is currently broken, but it shouldn't be. */
114 	.use_dma	= false
115 };
116 
117 static struct ofw_compat_data compat_data[] = {
118 	{"broadcom,bcm2835-sdhci",	(uintptr_t)&bcm2835_sdhci_conf},
119 	{"brcm,bcm2835-sdhci",		(uintptr_t)&bcm2835_sdhci_conf},
120 	{"brcm,bcm2835-mmc",		(uintptr_t)&bcm2835_sdhci_conf},
121 	{"brcm,bcm2711-emmc2",		(uintptr_t)&bcm2838_emmc2_conf},
122 	{"brcm,bcm2838-emmc2",		(uintptr_t)&bcm2838_emmc2_conf},
123 	{NULL,				0}
124 };
125 
126 TUNABLE_INT("hw.bcm2835.sdhci.hs", &bcm2835_sdhci_hs);
127 TUNABLE_INT("hw.bcm2835.sdhci.pio_mode", &bcm2835_sdhci_pio_mode);
128 
129 struct bcm_sdhci_softc {
130 	device_t		sc_dev;
131 	struct resource *	sc_mem_res;
132 	struct resource *	sc_irq_res;
133 	bus_space_tag_t		sc_bst;
134 	bus_space_handle_t	sc_bsh;
135 	void *			sc_intrhand;
136 	struct mmc_request *	sc_req;
137 	struct sdhci_slot	sc_slot;
138 	int			sc_dma_ch;
139 	bus_dma_tag_t		sc_dma_tag;
140 	bus_dmamap_t		sc_dma_map;
141 	vm_paddr_t		sc_sdhci_buffer_phys;
142 	bus_addr_t		dmamap_seg_addrs[NUM_DMA_SEGS];
143 	bus_size_t		dmamap_seg_sizes[NUM_DMA_SEGS];
144 	int			dmamap_seg_count;
145 	int			dmamap_seg_index;
146 	int			dmamap_status;
147 	uint32_t		blksz_and_count;
148 	uint32_t		cmd_and_mode;
149 	bool			need_update_blk;
150 #ifdef NOTYET
151 	device_t		clkman;
152 #endif
153 	struct bcm_mmc_conf *	conf;
154 };
155 
156 static int bcm_sdhci_probe(device_t);
157 static int bcm_sdhci_attach(device_t);
158 static int bcm_sdhci_detach(device_t);
159 static void bcm_sdhci_intr(void *);
160 
161 static int bcm_sdhci_get_ro(device_t, device_t);
162 static void bcm_sdhci_dma_intr(int ch, void *arg);
163 
164 static void
165 bcm_sdhci_dmacb(void *arg, bus_dma_segment_t *segs, int nseg, int err)
166 {
167 	struct bcm_sdhci_softc *sc = arg;
168 	int i;
169 
170 	sc->dmamap_status = err;
171 	sc->dmamap_seg_count = nseg;
172 
173 	/* Note nseg is guaranteed to be zero if err is non-zero. */
174 	for (i = 0; i < nseg; i++) {
175 		sc->dmamap_seg_addrs[i] = segs[i].ds_addr;
176 		sc->dmamap_seg_sizes[i] = segs[i].ds_len;
177 	}
178 }
179 
180 static int
181 bcm_sdhci_probe(device_t dev)
182 {
183 
184 	if (!ofw_bus_status_okay(dev))
185 		return (ENXIO);
186 
187 	if (ofw_bus_search_compatible(dev, compat_data)->ocd_data == 0)
188 		return (ENXIO);
189 
190 	device_set_desc(dev, "Broadcom 2708 SDHCI controller");
191 
192 	return (BUS_PROBE_DEFAULT);
193 }
194 
195 static int
196 bcm_sdhci_attach(device_t dev)
197 {
198 	struct bcm_sdhci_softc *sc = device_get_softc(dev);
199 	int rid, err;
200 	phandle_t node;
201 	pcell_t cell;
202 	u_int default_freq;
203 
204 	sc->sc_dev = dev;
205 	sc->sc_req = NULL;
206 
207 	sc->conf = (struct bcm_mmc_conf *)ofw_bus_search_compatible(dev,
208 	    compat_data)->ocd_data;
209 	if (sc->conf == 0)
210 	    return (ENXIO);
211 
212 	err = bcm2835_mbox_set_power_state(BCM2835_MBOX_POWER_ID_EMMC, TRUE);
213 	if (err != 0) {
214 		if (bootverbose)
215 			device_printf(dev, "Unable to enable the power\n");
216 		return (err);
217 	}
218 
219 	default_freq = 0;
220 	err = bcm2835_mbox_get_clock_rate(sc->conf->clock_id, &default_freq);
221 	if (err == 0) {
222 		/* Convert to MHz */
223 		default_freq /= 1000000;
224 	}
225 	if (default_freq == 0) {
226 		node = ofw_bus_get_node(sc->sc_dev);
227 		if ((OF_getencprop(node, "clock-frequency", &cell,
228 		    sizeof(cell))) > 0)
229 			default_freq = cell / 1000000;
230 	}
231 	if (default_freq == 0)
232 		default_freq = sc->conf->default_freq;
233 
234 	if (bootverbose)
235 		device_printf(dev, "SDHCI frequency: %dMHz\n", default_freq);
236 #ifdef NOTYET
237 	if (sc->conf->clock_src > 0) {
238 		uint32_t f;
239 		sc->clkman = devclass_get_device(devclass_find("bcm2835_clkman"), 0);
240 		if (sc->clkman == NULL) {
241 			device_printf(dev, "cannot find Clock Manager\n");
242 			return (ENXIO);
243 		}
244 
245 		f = bcm2835_clkman_set_frequency(sc->clkman, sc->conf->clock_src, default_freq);
246 		if (f == 0)
247 			return (EINVAL);
248 
249 		if (bootverbose)
250 			device_printf(dev, "Clock source frequency: %dMHz\n", f);
251 	}
252 #endif
253 
254 	rid = 0;
255 	sc->sc_mem_res = bus_alloc_resource_any(dev, SYS_RES_MEMORY, &rid,
256 	    RF_ACTIVE);
257 	if (!sc->sc_mem_res) {
258 		device_printf(dev, "cannot allocate memory window\n");
259 		err = ENXIO;
260 		goto fail;
261 	}
262 
263 	sc->sc_bst = rman_get_bustag(sc->sc_mem_res);
264 	sc->sc_bsh = rman_get_bushandle(sc->sc_mem_res);
265 
266 	rid = 0;
267 	sc->sc_irq_res = bus_alloc_resource_any(dev, SYS_RES_IRQ, &rid,
268 	    RF_ACTIVE | RF_SHAREABLE);
269 	if (!sc->sc_irq_res) {
270 		device_printf(dev, "cannot allocate interrupt\n");
271 		err = ENXIO;
272 		goto fail;
273 	}
274 
275 	if (bus_setup_intr(dev, sc->sc_irq_res, INTR_TYPE_BIO | INTR_MPSAFE,
276 	    NULL, bcm_sdhci_intr, sc, &sc->sc_intrhand)) {
277 		device_printf(dev, "cannot setup interrupt handler\n");
278 		err = ENXIO;
279 		goto fail;
280 	}
281 
282 	if (!bcm2835_sdhci_pio_mode)
283 		sc->sc_slot.opt = SDHCI_PLATFORM_TRANSFER;
284 
285 	sc->sc_slot.caps = SDHCI_CAN_VDD_330 | SDHCI_CAN_VDD_180;
286 	if (bcm2835_sdhci_hs)
287 		sc->sc_slot.caps |= SDHCI_CAN_DO_HISPD;
288 	sc->sc_slot.caps |= (default_freq << SDHCI_CLOCK_BASE_SHIFT);
289 	sc->sc_slot.quirks = sc->conf->quirks;
290 
291 	sdhci_init_slot(dev, &sc->sc_slot, 0);
292 
293 	if (sc->conf->use_dma) {
294 		sc->sc_dma_ch = bcm_dma_allocate(BCM_DMA_CH_ANY);
295 		if (sc->sc_dma_ch == BCM_DMA_CH_INVALID)
296 			goto fail;
297 
298 		if (bcm_dma_setup_intr(sc->sc_dma_ch, bcm_sdhci_dma_intr, sc) != 0) {
299 			device_printf(dev, "cannot setup dma interrupt handler\n");
300 			err = ENXIO;
301 			goto fail;
302 		}
303 
304 		/* Allocate bus_dma resources. */
305 		err = bus_dma_tag_create(bus_get_dma_tag(dev),
306 		    1, 0, BUS_SPACE_MAXADDR_32BIT,
307 		    BUS_SPACE_MAXADDR, NULL, NULL,
308 		    BCM_SDHCI_BUFFER_SIZE, NUM_DMA_SEGS, BCM_SDHCI_BUFFER_SIZE,
309 		    BUS_DMA_ALLOCNOW, NULL, NULL,
310 		    &sc->sc_dma_tag);
311 
312 		if (err) {
313 			device_printf(dev, "failed allocate DMA tag");
314 			goto fail;
315 		}
316 
317 		err = bus_dmamap_create(sc->sc_dma_tag, 0, &sc->sc_dma_map);
318 		if (err) {
319 			device_printf(dev, "bus_dmamap_create failed\n");
320 			goto fail;
321 		}
322 	}
323 
324 	/* FIXME: Fix along with other BUS_SPACE_PHYSADDR instances */
325 	sc->sc_sdhci_buffer_phys = rman_get_start(sc->sc_mem_res) +
326 	    SDHCI_BUFFER;
327 
328 	bus_generic_probe(dev);
329 	bus_generic_attach(dev);
330 
331 	sdhci_start_slot(&sc->sc_slot);
332 
333 	/* Seed our copies. */
334 	sc->blksz_and_count = SDHCI_READ_4(dev, &sc->sc_slot, SDHCI_BLOCK_SIZE);
335 	sc->cmd_and_mode = SDHCI_READ_4(dev, &sc->sc_slot, SDHCI_TRANSFER_MODE);
336 
337 	return (0);
338 
339 fail:
340 	if (sc->sc_intrhand)
341 		bus_teardown_intr(dev, sc->sc_irq_res, sc->sc_intrhand);
342 	if (sc->sc_irq_res)
343 		bus_release_resource(dev, SYS_RES_IRQ, 0, sc->sc_irq_res);
344 	if (sc->sc_mem_res)
345 		bus_release_resource(dev, SYS_RES_MEMORY, 0, sc->sc_mem_res);
346 
347 	return (err);
348 }
349 
350 static int
351 bcm_sdhci_detach(device_t dev)
352 {
353 
354 	return (EBUSY);
355 }
356 
357 static void
358 bcm_sdhci_intr(void *arg)
359 {
360 	struct bcm_sdhci_softc *sc = arg;
361 
362 	sdhci_generic_intr(&sc->sc_slot);
363 }
364 
365 static int
366 bcm_sdhci_get_ro(device_t bus, device_t child)
367 {
368 
369 	return (0);
370 }
371 
372 static inline uint32_t
373 RD4(struct bcm_sdhci_softc *sc, bus_size_t off)
374 {
375 	uint32_t val = bus_space_read_4(sc->sc_bst, sc->sc_bsh, off);
376 	return val;
377 }
378 
379 static inline void
380 WR4(struct bcm_sdhci_softc *sc, bus_size_t off, uint32_t val)
381 {
382 
383 	bus_space_write_4(sc->sc_bst, sc->sc_bsh, off, val);
384 	/*
385 	 * The Arasan HC has a bug where it may lose the content of
386 	 * consecutive writes to registers that are within two SD-card
387 	 * clock cycles of each other (a clock domain crossing problem).
388 	 */
389 	if (sc->sc_slot.clock > 0)
390 		DELAY(((2 * 1000000) / sc->sc_slot.clock) + 1);
391 }
392 
393 static uint8_t
394 bcm_sdhci_read_1(device_t dev, struct sdhci_slot *slot, bus_size_t off)
395 {
396 	struct bcm_sdhci_softc *sc = device_get_softc(dev);
397 	uint32_t val = RD4(sc, off & ~3);
398 
399 	return ((val >> (off & 3)*8) & 0xff);
400 }
401 
402 static uint16_t
403 bcm_sdhci_read_2(device_t dev, struct sdhci_slot *slot, bus_size_t off)
404 {
405 	struct bcm_sdhci_softc *sc = device_get_softc(dev);
406 	uint32_t val32;
407 
408 	/*
409 	 * Standard 32-bit handling of command and transfer mode, as
410 	 * well as block size and count.
411 	 */
412 	if ((off == SDHCI_BLOCK_SIZE || off == SDHCI_BLOCK_COUNT) &&
413 	    sc->need_update_blk)
414 		val32 = sc->blksz_and_count;
415 	else if (off == SDHCI_TRANSFER_MODE || off == SDHCI_COMMAND_FLAGS)
416 		val32 = sc->cmd_and_mode;
417 	else
418 		val32 = RD4(sc, off & ~3);
419 
420 	return ((val32 >> (off & 3)*8) & 0xffff);
421 }
422 
423 static uint32_t
424 bcm_sdhci_read_4(device_t dev, struct sdhci_slot *slot, bus_size_t off)
425 {
426 	struct bcm_sdhci_softc *sc = device_get_softc(dev);
427 
428 	return RD4(sc, off);
429 }
430 
431 static void
432 bcm_sdhci_read_multi_4(device_t dev, struct sdhci_slot *slot, bus_size_t off,
433     uint32_t *data, bus_size_t count)
434 {
435 	struct bcm_sdhci_softc *sc = device_get_softc(dev);
436 
437 	bus_space_read_multi_4(sc->sc_bst, sc->sc_bsh, off, data, count);
438 }
439 
440 static void
441 bcm_sdhci_write_1(device_t dev, struct sdhci_slot *slot, bus_size_t off, uint8_t val)
442 {
443 	struct bcm_sdhci_softc *sc = device_get_softc(dev);
444 	uint32_t val32 = RD4(sc, off & ~3);
445 	val32 &= ~(0xff << (off & 3)*8);
446 	val32 |= (val << (off & 3)*8);
447 	WR4(sc, off & ~3, val32);
448 }
449 
450 static void
451 bcm_sdhci_write_2(device_t dev, struct sdhci_slot *slot, bus_size_t off, uint16_t val)
452 {
453 	struct bcm_sdhci_softc *sc = device_get_softc(dev);
454 	uint32_t val32;
455 
456 	/*
457 	 * If we have a queued up 16bit value for blk size or count, use and
458 	 * update the saved value rather than doing any real register access.
459 	 * If we did not touch either since the last write, then read from
460 	 * register as at least block count can change.
461 	 * Similarly, if we are about to issue a command, always use the saved
462 	 * value for transfer mode as we can never write that without issuing
463 	 * a command.
464 	 */
465 	if ((off == SDHCI_BLOCK_SIZE || off == SDHCI_BLOCK_COUNT) &&
466 	    sc->need_update_blk)
467 		val32 = sc->blksz_and_count;
468 	else if (off == SDHCI_COMMAND_FLAGS)
469 		val32 = sc->cmd_and_mode;
470 	else
471 		val32 = RD4(sc, off & ~3);
472 
473 	val32 &= ~(0xffff << (off & 3)*8);
474 	val32 |= (val << (off & 3)*8);
475 
476 	if (off == SDHCI_TRANSFER_MODE)
477 		sc->cmd_and_mode = val32;
478 	else if (off == SDHCI_BLOCK_SIZE || off == SDHCI_BLOCK_COUNT) {
479 		sc->blksz_and_count = val32;
480 		sc->need_update_blk = true;
481 	} else {
482 		if (off == SDHCI_COMMAND_FLAGS) {
483 			/* If we saved blk writes, do them now before cmd. */
484 			if (sc->need_update_blk) {
485 				WR4(sc, SDHCI_BLOCK_SIZE, sc->blksz_and_count);
486 				sc->need_update_blk = false;
487 			}
488 			/* Always save cmd and mode registers. */
489 			sc->cmd_and_mode = val32;
490 		}
491 		WR4(sc, off & ~3, val32);
492 	}
493 }
494 
495 static void
496 bcm_sdhci_write_4(device_t dev, struct sdhci_slot *slot, bus_size_t off, uint32_t val)
497 {
498 	struct bcm_sdhci_softc *sc = device_get_softc(dev);
499 	WR4(sc, off, val);
500 }
501 
502 static void
503 bcm_sdhci_write_multi_4(device_t dev, struct sdhci_slot *slot, bus_size_t off,
504     uint32_t *data, bus_size_t count)
505 {
506 	struct bcm_sdhci_softc *sc = device_get_softc(dev);
507 
508 	bus_space_write_multi_4(sc->sc_bst, sc->sc_bsh, off, data, count);
509 }
510 
511 static void
512 bcm_sdhci_start_dma_seg(struct bcm_sdhci_softc *sc)
513 {
514 	struct sdhci_slot *slot;
515 	vm_paddr_t pdst, psrc;
516 	int err, idx, len, sync_op, width;
517 
518 	slot = &sc->sc_slot;
519 	idx = sc->dmamap_seg_index++;
520 	len = sc->dmamap_seg_sizes[idx];
521 	slot->offset += len;
522 	width = (len & 0xf ? BCM_DMA_32BIT : BCM_DMA_128BIT);
523 
524 	if (slot->curcmd->data->flags & MMC_DATA_READ) {
525 		bcm_dma_setup_src(sc->sc_dma_ch, BCM_DMA_DREQ_EMMC,
526 		    BCM_DMA_SAME_ADDR, BCM_DMA_32BIT);
527 		bcm_dma_setup_dst(sc->sc_dma_ch, BCM_DMA_DREQ_NONE,
528 		    BCM_DMA_INC_ADDR, width);
529 		psrc = sc->sc_sdhci_buffer_phys;
530 		pdst = sc->dmamap_seg_addrs[idx];
531 		sync_op = BUS_DMASYNC_PREREAD;
532 	} else {
533 		bcm_dma_setup_src(sc->sc_dma_ch, BCM_DMA_DREQ_NONE,
534 		    BCM_DMA_INC_ADDR, width);
535 		bcm_dma_setup_dst(sc->sc_dma_ch, BCM_DMA_DREQ_EMMC,
536 		    BCM_DMA_SAME_ADDR, BCM_DMA_32BIT);
537 		psrc = sc->dmamap_seg_addrs[idx];
538 		pdst = sc->sc_sdhci_buffer_phys;
539 		sync_op = BUS_DMASYNC_PREWRITE;
540 	}
541 
542 	/*
543 	 * When starting a new DMA operation do the busdma sync operation, and
544 	 * disable SDCHI data interrrupts because we'll be driven by DMA
545 	 * interrupts (or SDHCI error interrupts) until the IO is done.
546 	 */
547 	if (idx == 0) {
548 		bus_dmamap_sync(sc->sc_dma_tag, sc->sc_dma_map, sync_op);
549 		slot->intmask &= ~(SDHCI_INT_DATA_AVAIL |
550 		    SDHCI_INT_SPACE_AVAIL | SDHCI_INT_DATA_END);
551 		bcm_sdhci_write_4(sc->sc_dev, &sc->sc_slot, SDHCI_SIGNAL_ENABLE,
552 		    slot->intmask);
553 	}
554 
555 	/*
556 	 * Start the DMA transfer.  Only programming errors (like failing to
557 	 * allocate a channel) cause a non-zero return from bcm_dma_start().
558 	 */
559 	err = bcm_dma_start(sc->sc_dma_ch, psrc, pdst, len);
560 	KASSERT((err == 0), ("bcm2835_sdhci: failed DMA start"));
561 }
562 
563 static void
564 bcm_sdhci_dma_intr(int ch, void *arg)
565 {
566 	struct bcm_sdhci_softc *sc = (struct bcm_sdhci_softc *)arg;
567 	struct sdhci_slot *slot = &sc->sc_slot;
568 	uint32_t reg, mask;
569 	int left, sync_op;
570 
571 	mtx_lock(&slot->mtx);
572 
573 	if (slot->curcmd == NULL) {
574 		mtx_unlock(&slot->mtx);
575 		device_printf(sc->sc_dev,
576 		    "command aborted in the middle of DMA\n");
577 		return;
578 	}
579 
580 	/*
581 	 * If there are more segments for the current dma, start the next one.
582 	 * Otherwise unload the dma map and decide what to do next based on the
583 	 * status of the sdhci controller and whether there's more data left.
584 	 */
585 	if (sc->dmamap_seg_index < sc->dmamap_seg_count) {
586 		bcm_sdhci_start_dma_seg(sc);
587 		mtx_unlock(&slot->mtx);
588 		return;
589 	}
590 
591 	if (slot->curcmd->data->flags & MMC_DATA_READ) {
592 		sync_op = BUS_DMASYNC_POSTREAD;
593 		mask = SDHCI_INT_DATA_AVAIL;
594 	} else {
595 		sync_op = BUS_DMASYNC_POSTWRITE;
596 		mask = SDHCI_INT_SPACE_AVAIL;
597 	}
598 	bus_dmamap_sync(sc->sc_dma_tag, sc->sc_dma_map, sync_op);
599 	bus_dmamap_unload(sc->sc_dma_tag, sc->sc_dma_map);
600 
601 	sc->dmamap_seg_count = 0;
602 	sc->dmamap_seg_index = 0;
603 
604 	left = min(BCM_SDHCI_BUFFER_SIZE,
605 	    slot->curcmd->data->len - slot->offset);
606 
607 	/*
608 	 * If there is less than buffer size outstanding, we would not handle
609 	 * it anymore using DMA if bcm_sdhci_will_handle_transfer() were asked.
610 	 * Re-enable interrupts and return and let the SDHCI state machine
611 	 * finish the job.
612 	 */
613 	if (left < BCM_SDHCI_BUFFER_SIZE) {
614 		/* Re-enable data interrupts. */
615 		slot->intmask |= SDHCI_INT_DATA_AVAIL | SDHCI_INT_SPACE_AVAIL |
616 		    SDHCI_INT_DATA_END;
617 		bcm_sdhci_write_4(slot->bus, slot, SDHCI_SIGNAL_ENABLE,
618 		    slot->intmask);
619 		mtx_unlock(&slot->mtx);
620 		return;
621 	}
622 
623 	/* DATA END? */
624 	reg = bcm_sdhci_read_4(slot->bus, slot, SDHCI_INT_STATUS);
625 
626 	if (reg & SDHCI_INT_DATA_END) {
627 		/* ACK for all outstanding interrupts */
628 		bcm_sdhci_write_4(slot->bus, slot, SDHCI_INT_STATUS, reg);
629 
630 		/* enable INT */
631 		slot->intmask |= SDHCI_INT_DATA_AVAIL | SDHCI_INT_SPACE_AVAIL
632 		    | SDHCI_INT_DATA_END;
633 		bcm_sdhci_write_4(slot->bus, slot, SDHCI_SIGNAL_ENABLE,
634 		    slot->intmask);
635 
636 		/* finish this data */
637 		sdhci_finish_data(slot);
638 	}
639 	else {
640 		/* already available? */
641 		if (reg & mask) {
642 
643 			/* ACK for DATA_AVAIL or SPACE_AVAIL */
644 			bcm_sdhci_write_4(slot->bus, slot,
645 			    SDHCI_INT_STATUS, mask);
646 
647 			/* continue next DMA transfer */
648 			if (bus_dmamap_load(sc->sc_dma_tag, sc->sc_dma_map,
649 			    (uint8_t *)slot->curcmd->data->data +
650 			    slot->offset, left, bcm_sdhci_dmacb, sc,
651 			    BUS_DMA_NOWAIT) != 0 || sc->dmamap_status != 0) {
652 				slot->curcmd->error = MMC_ERR_NO_MEMORY;
653 				sdhci_finish_data(slot);
654 			} else {
655 				bcm_sdhci_start_dma_seg(sc);
656 			}
657 		} else {
658 			/* wait for next data by INT */
659 
660 			/* enable INT */
661 			slot->intmask |= SDHCI_INT_DATA_AVAIL |
662 			    SDHCI_INT_SPACE_AVAIL | SDHCI_INT_DATA_END;
663 			bcm_sdhci_write_4(slot->bus, slot, SDHCI_SIGNAL_ENABLE,
664 			    slot->intmask);
665 		}
666 	}
667 
668 	mtx_unlock(&slot->mtx);
669 }
670 
671 static void
672 bcm_sdhci_read_dma(device_t dev, struct sdhci_slot *slot)
673 {
674 	struct bcm_sdhci_softc *sc = device_get_softc(slot->bus);
675 	size_t left;
676 
677 	if (sc->dmamap_seg_count != 0) {
678 		device_printf(sc->sc_dev, "DMA in use\n");
679 		return;
680 	}
681 
682 	left = min(BCM_SDHCI_BUFFER_SIZE,
683 	    slot->curcmd->data->len - slot->offset);
684 
685 	KASSERT((left & 3) == 0,
686 	    ("%s: len = %zu, not word-aligned", __func__, left));
687 
688 	if (bus_dmamap_load(sc->sc_dma_tag, sc->sc_dma_map,
689 	    (uint8_t *)slot->curcmd->data->data + slot->offset, left,
690 	    bcm_sdhci_dmacb, sc, BUS_DMA_NOWAIT) != 0 ||
691 	    sc->dmamap_status != 0) {
692 		slot->curcmd->error = MMC_ERR_NO_MEMORY;
693 		return;
694 	}
695 
696 	/* DMA start */
697 	bcm_sdhci_start_dma_seg(sc);
698 }
699 
700 static void
701 bcm_sdhci_write_dma(device_t dev, struct sdhci_slot *slot)
702 {
703 	struct bcm_sdhci_softc *sc = device_get_softc(slot->bus);
704 	size_t left;
705 
706 	if (sc->dmamap_seg_count != 0) {
707 		device_printf(sc->sc_dev, "DMA in use\n");
708 		return;
709 	}
710 
711 	left = min(BCM_SDHCI_BUFFER_SIZE,
712 	    slot->curcmd->data->len - slot->offset);
713 
714 	KASSERT((left & 3) == 0,
715 	    ("%s: len = %zu, not word-aligned", __func__, left));
716 
717 	if (bus_dmamap_load(sc->sc_dma_tag, sc->sc_dma_map,
718 	    (uint8_t *)slot->curcmd->data->data + slot->offset, left,
719 	    bcm_sdhci_dmacb, sc, BUS_DMA_NOWAIT) != 0 ||
720 	    sc->dmamap_status != 0) {
721 		slot->curcmd->error = MMC_ERR_NO_MEMORY;
722 		return;
723 	}
724 
725 	/* DMA start */
726 	bcm_sdhci_start_dma_seg(sc);
727 }
728 
729 static int
730 bcm_sdhci_will_handle_transfer(device_t dev, struct sdhci_slot *slot)
731 {
732 	struct bcm_sdhci_softc *sc = device_get_softc(slot->bus);
733 	size_t left;
734 
735 	if (!sc->conf->use_dma)
736 		return (0);
737 
738 	/*
739 	 * Do not use DMA for transfers less than block size or with a length
740 	 * that is not a multiple of four.
741 	 */
742 	left = min(BCM_DMA_BLOCK_SIZE,
743 	    slot->curcmd->data->len - slot->offset);
744 	if (left < BCM_DMA_BLOCK_SIZE)
745 		return (0);
746 	if (left & 0x03)
747 		return (0);
748 
749 	return (1);
750 }
751 
752 static void
753 bcm_sdhci_start_transfer(device_t dev, struct sdhci_slot *slot,
754     uint32_t *intmask)
755 {
756 
757 	/* DMA transfer FIFO 1KB */
758 	if (slot->curcmd->data->flags & MMC_DATA_READ)
759 		bcm_sdhci_read_dma(dev, slot);
760 	else
761 		bcm_sdhci_write_dma(dev, slot);
762 }
763 
764 static void
765 bcm_sdhci_finish_transfer(device_t dev, struct sdhci_slot *slot)
766 {
767 
768 	sdhci_finish_data(slot);
769 }
770 
771 static device_method_t bcm_sdhci_methods[] = {
772 	/* Device interface */
773 	DEVMETHOD(device_probe,		bcm_sdhci_probe),
774 	DEVMETHOD(device_attach,	bcm_sdhci_attach),
775 	DEVMETHOD(device_detach,	bcm_sdhci_detach),
776 
777 	/* Bus interface */
778 	DEVMETHOD(bus_read_ivar,	sdhci_generic_read_ivar),
779 	DEVMETHOD(bus_write_ivar,	sdhci_generic_write_ivar),
780 	DEVMETHOD(bus_add_child,	bus_generic_add_child),
781 
782 	/* MMC bridge interface */
783 	DEVMETHOD(mmcbr_update_ios,	sdhci_generic_update_ios),
784 	DEVMETHOD(mmcbr_request,	sdhci_generic_request),
785 	DEVMETHOD(mmcbr_get_ro,		bcm_sdhci_get_ro),
786 	DEVMETHOD(mmcbr_acquire_host,	sdhci_generic_acquire_host),
787 	DEVMETHOD(mmcbr_release_host,	sdhci_generic_release_host),
788 
789 	/* Platform transfer methods */
790 	DEVMETHOD(sdhci_platform_will_handle,		bcm_sdhci_will_handle_transfer),
791 	DEVMETHOD(sdhci_platform_start_transfer,	bcm_sdhci_start_transfer),
792 	DEVMETHOD(sdhci_platform_finish_transfer,	bcm_sdhci_finish_transfer),
793 	/* SDHCI registers accessors */
794 	DEVMETHOD(sdhci_read_1,		bcm_sdhci_read_1),
795 	DEVMETHOD(sdhci_read_2,		bcm_sdhci_read_2),
796 	DEVMETHOD(sdhci_read_4,		bcm_sdhci_read_4),
797 	DEVMETHOD(sdhci_read_multi_4,	bcm_sdhci_read_multi_4),
798 	DEVMETHOD(sdhci_write_1,	bcm_sdhci_write_1),
799 	DEVMETHOD(sdhci_write_2,	bcm_sdhci_write_2),
800 	DEVMETHOD(sdhci_write_4,	bcm_sdhci_write_4),
801 	DEVMETHOD(sdhci_write_multi_4,	bcm_sdhci_write_multi_4),
802 
803 	DEVMETHOD_END
804 };
805 
806 static devclass_t bcm_sdhci_devclass;
807 
808 static driver_t bcm_sdhci_driver = {
809 	"sdhci_bcm",
810 	bcm_sdhci_methods,
811 	sizeof(struct bcm_sdhci_softc),
812 };
813 
814 DRIVER_MODULE(sdhci_bcm, simplebus, bcm_sdhci_driver, bcm_sdhci_devclass,
815     NULL, NULL);
816 #ifdef NOTYET
817 MODULE_DEPEND(sdhci_bcm, bcm2835_clkman, 1, 1, 1);
818 #endif
819 SDHCI_DEPEND(sdhci_bcm);
820 #ifndef MMCCAM
821 MMC_DECLARE_BRIDGE(sdhci_bcm);
822 #endif
823